Various structures for transparent touch switches that can detect input position have been proposed such as a transparent electrostatic capacitive touch switch. For example, Patent Document 1 discloses a transparent touch switch comprising a dielectric layer lying between a pair of transparent planar bodies each provided with a transparent conductive film patterned into a predetermined shape. When an operator touches the operation surface with a finger, etc., the transparent touch switch detects the touched position by sensing the change of electric capacity via grounding through a human body.
Such a transparent touch switch is mounted on the surface of a liquid crystal display apparatus, CRT or the like. In this structure, the shape of the pattern of the transparent electric conduction film that is formed in the transparent planar body becomes conspicuous, lowering visibility of the touch switch.
A transparent conductive film disclosed in Patent Document 2 is one example of the known transparent planar body. The transparent conductive film comprises an undercoat layer between a conductive-layer formation film and a conductive layer. The undercoat layer is formed from two layers having different refractive indices. Specifically, a highly refractive zinc oxide/tin oxide film having a thickness of 600 Å is disposed near the conductive-layer formation film and a lower refractive silicon oxide film having a thickness of 450 Å is disposed near the conductive layer.
When this transparent conductive film is used as a transparent electrostatic capacitive touch switch, the pattern shape of the conductive layer also becomes conspicuous, and therefore there is room for improvement in this respect.
[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-173238 (FIGS. 1 and 5)
[Patent Document 2] Japanese Unexamined Patent Publication No. 2003-197035 (Table 1)